The invention relates to processing of video image data and, more particularly, to a method for the processing of video image data associated with a document imaging system. Still more specifically, the invention pertains to a method for distinguishing between useful data on the document and expendable background image data associated with that document and for discarding the expendable background data in order to effect more efficient storage and handling of the image data for the document.
Financial documents, such as checks, usually contain a plurality of characters printed in magnetic ink capable of being read by a sorter which automatically sorts such checks into a plurality of bins. Prior to sorting, these documents are physically handled by financial institution employees who enter the handwritten or typed dollar amount onto the check also with magnetic ink by the use of specialized amount entry equipment. Additionally, the employees physically enter any corrections associated with the reading of the magnetic ink code upon each of the sorted checks.
These prior techniques of utilizing employees to process financial documents have proven to be relatively labor intensive, inefficient and prone to human error. Many of the checks are lost, destroyed or mutilated during their physical handling. Additionally, the speed associated with the processing of the documents is limited to the processing capability of the employees and the particular mechanical amount entry equipment used by them.
The banking industry is now considering the adoption of electronic image data processing to eventually supplant the physical handling of documents such as checks by employees. As part of such image processing systems under consideration is a pre-processing technique on image data which deletes (or suppresses) non-useful background image data while retaining only useful information contained within such image data. Known techniques for background suppression for document images suffer from disadvantages of being incapable of retaining low contrast useful signal data which is located within the image in an all-white "box" region or removal of medium contrast textured document backgrounds.